By way of introduction, it is known the problem related to the maintenance and cleaning of wind turbine blades as both the mast itself; since, due to the vertical construction and large height of the wind turbines themselves as well as the places where they are located, which are usually hard-to-access areas such as mountain peaks or sea areas, their maintenance and cleaning require highly qualified workers and highly specific techniques in order to successfully carry out said maintenance and cleaning tasks.
In this sense, the technique that is most commonly used for exterior cleaning on wind turbine towers involves vertical work by skilled workers, which have a lifeline and a hoist-type anchoring system that sustains said worker from the top portion of the mast, known as nacelle, to the base of the mast itself; thus, the worker proceeds to go sliding down and cleaning the outer surface of the mast with pressurized guns or similar cleaning means. However, said technique has a series of drawbacks:                First of all and most importantly, workers' safety is a big concern, since vertical jobs pose a high risk of falls or impacting the mast itself, since at the areas above of the mast the existing wind can be of high intensity, due to both the height of the mast itself and the location of the wind turbine, which is strategically defined to have the highest possible amount of wind energy.        Secondly, the high cost of employing two or more workers who are in charge of to do said maintenance and cleaning tasks, in addition to the associated specific cleaning equipment.        Finally, the slow response capacity stands towards the owner of the wind turbine, since they depend on the availability of workers of the maintenance and cleaning external companies themselves.        
In order to solve these problems, the use of wind turbine cleaning helicopters, which are provided with a tank having cleaning products inside it, as well as one or several pressurized guns, which are operated by workers from inside the helicopter, is generally known; even though it is possible with this maintenance and cleaning alternative to prevent the risk for the health and safety of the workers, since the vertical work as such is done away with, it presents other drawbacks, such as:                The cost of using a helicopter to perform said maintenance tasks is very high by the renting the helicopter, the fuel, the pilot and at least another employee responsible for cleaning said wind turbine.        The risk of getting a helicopter near a wind turbine which, as previously indicated, is located in windy places that can lead air currents that make difficult the helicopter flight, and thus the safety of its occupants.        Finally, again, the slow responsiveness towards the owner of the wind turbine, since it depends on the availability of the helicopter, as well as the pilot and workers of the maintenance and cleaning external companies themselves.        
This is why, in view of the existing drawbacks during maintenance and cleaning wind turbine towers, the appearance of a new exterior cleaning machine in wind turbine-towers capable of solving the preceding problems is necessary, such that no vertical work by workers is required, thus preventing the risk of work accidents as much as possible; such that the machine which is the object of the invention does not require high purchase or maintenance cost, so that several machines may be stored in nearby areas, thus guaranteeing fast response capabilities towards the owner of the wind turbine; which can further clean any outer surface of the mast of the wind turbine in a fast and efficient manner; all of the above using a cleaning machine that is simple, easy to install and maintenance, and economically competitive with regard to the state of the art known to date.